Methionine and cystine requirements of slow- and fast-feathering male broilers from zero to three weeks of age.

Auburn University, Poultry Science, Auburn, Alabama 36849, USA.
Poultry Science (Impact Factor: 1.52). 10/2003; 82(9):1423-7. DOI: 10.1093/ps/82.9.1423
Source: PubMed

ABSTRACT Two experiments were conducted with fast- (Ross x 3F8) and slow- (Ross x 308) feathering broiler males from 0 to 3 wk of age to determine Met and Cys requirements. A corn-soybean meal basal diet was formulated to be deficient in Met and Cys but was adequate in all other nutrients (22.0% CP; 3,050 kcal ME/kg). In experiment 1, diets contained 0.50% dietary Cys with 0.35, 0.40, 0.45, and 0.50% total Met. Feed conversion (FC) of slow- and fast-feathering males improved in a similar manner to 0.50% Met (linear, P < 0.05). Nitrogen retention measured from 20 to 21 d of age optimized at 0.46% Met (quadratic, P < 0.01), regardless of feathering rate. Experiment 2 examined the response to feeding 0.35, 0.40, 0.45, and 0.50% total Cys in diets having total Met at 0.45%. Increasing Cys improved FC that optimized at 0.40% with fast-feathering birds (quadratic, P < 0.01), whereas slow-feathering broilers were not responsive. Nitrogen retention measured from d 20 to 21 did not indicate a difference attributable to feathering but a Cys optimization at 0.43% with both broiler sources. Present experimentation indicates a Met requirement approximating 0.50% is appropriate for broilers 0 to 3 wk of age, regardless of feather rate; however, the estimated Cys requirement for slow-feathering males (0.39%) was less than for fast-feathering (0.44%) males.

1 Bookmark
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This summary focuses on reducing nitrogen (N) and ammonia emissions from poultry manure through the use of improved amino acid digestibilities and enzyme supplementation. Proper feed processing techniques, phase feeding, and the minimization of feed and water waste can contribute to additional minor reductions in these emissions. Reductions in environmental pollution can be achieved through improved diet formulation based on available nutrients in the ingredients, reducing crude protein (CP) levels and adding synthetic amino acids. Use of amino acid and CP digestibilities can reduce N excretion up to 40% and a 25% increase in N digestibility can be achieved with enzyme supplementation in broiler diets. Digestibilities can be measured by two methods: the excreta and ileal amino acid digestibilities. Both methods allow amino acid levels to be reduced by 10% or more. Enzyme supplementation decreases intestinal viscosity, improves metabolizable energy levels, and increases amino acid digestibilities. Many feed manufacturers still use total amino acid content to formulate feeds. To meet amino acid requirements, crystalline amino acids are needed. The use of feather, meat and bone meal must not be overestimated or underestimated and the limiting amino acids such as cystine, tryptophan, and threonine must be carefully analyzed.
    Bioresource Technology 10/2007; 98(12):2282-300. · 5.04 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The main objective of this experiment was to study the effect of CP level in the diet on the efficiency of Met utilization. Male Ross broilers were grown in floor pens in groups of 10. Three pens were allocated 1 of 16 experimental diets from d 8 to 21 posthatch. Dietary Met concentration ranged from 1.8 to 7.0 g/kg with 183 (low protein; LP) or 229 (normal protein; NP) g of CP/kg of diet. Inclusion rates of DL-Met and nonessential amino acids were varied to achieve these differences. Prececal net disappearance was additionally studied for the NP diet without Met supplementation in 4 pens of 10 birds each. Net disappearances were 83 and 78% for CP and Met, respectively, and ranged from 66% (cystine) to 96% (Ala) for other amino acids. Birds significantly and nonlinearly responded to increased Met intake in BW gain, which was significantly lower for NP than for LP. Although the concentration of protein in gained BW was unaffected by Met and CP levels, the contents of fat and energy in gained BW were lower with NP than with LP and rose with increasing Met intake until a plateau was attained. The content of Met in accreted whole-body protein rose with increasing Met intake and plateaued at about 2.0 g/16 g of N. With the exception of Lys and Gly, Met intake did not significantly affect the concentration of amino acids in accreted whole-body protein. The marginal efficiency of Met utilization was, at its maximum, 8% lower with NP than with LP. Concentrations of 3.4 and 3.6 g of Met/kg of diet were needed to achieve 95% of ymax in protein accretion with LP and NP, respectively. It was concluded that an increase in the dietary Met requirement often found with elevated CP concentrations was the consequence of a reduced capacity to use Met for protein gain.
    Poultry Science 11/2005; 84(10):1584-92. · 1.52 Impact Factor
  • Journal of Applied Poultry Research - J APPL POULTRY RES. 01/2008; 17(1):157-167.


Available from